Amphiphilic peroxynitrite decomposition catalysts in liposomal assemblies

Area of Science:

• Biochemistry
• Materials Science
• Pharmacology

Background:

• Peroxynitrite (ONOO-) is a toxic oxidant implicated in various diseases.
• Water-soluble porphyrins like FeTMPyP and MnTMPyP are explored for ONOO- detoxification.
• Development of amphiphilic analogs for liposomal delivery is needed.

Purpose of the Study:

• To synthesize and evaluate amphiphilic iron and manganese porphyrins for ONOO- decomposition.
• To assess the efficacy of these porphyrins when incorporated into sterically stabilized liposomes (SLs).

Main Methods:

• Synthesis of amphiphilic iron (1a-c) and manganese (2a-c) porphyrins.
• Liposomal formulation and binding studies with dimyristoylphosphatidylcholine liposomes and SLs.
• Kinetic analysis of ONOO- decomposition catalyzed by metalloporphyrin-liposome constructs.

Main Results:

• PEG-linked metalloporphyrins (1b, 2b) demonstrated high catalytic activity for ONOO- decomposition (kcat up to 5.0 x 10^5 M^-1 s^-1).
• Metalloporphyrin-SL constructs also efficiently catalyzed ONOO- decomposition (kcat ~2 x 10^5 M^-1 s^-1).
• Non-PEGylated analogs (1a, 2a) showed significantly lower catalytic efficiency (kcat ~3.5 x 10^4 M^-1 s^-1).

Conclusions:

• The catalytic efficiency of amphiphilic metalloporphyrins depends on the polarity of their headgroup environment.
• A polar aqueous environment is crucial for effective ONOO- decomposition catalysis.
• PEG-linked metalloporphyrins in SLs are promising therapeutic agents for ONOO- related diseases.